Throughout the nuclear age, presidents have allowed their senior commanders to plan for the first use of nuclear weapons. Contingency plans were drawn to initiate first strikes to repel an invasion of Europe by the Soviet Union, defeat China and North Korea, take out chemical and biological weapons and conduct other missions.

After the end of the Cold War, which coincided with revolutionary advances in our nonnuclear military capacities, the range of these missions steadily narrowed to the point where nuclear weapons today no longer serve any purpose beyond deterring the first use of such weapons by our adversaries. Our nonnuclear strength, including economic and diplomatic power, our alliances, our conventional and cyber weaponry and our technological advantages, constitute a global military juggernaut unmatched in history. The United States simply does not need nuclear weapons to defend its own and its allies’ vital interests, as long as our adversaries refrain from their use.

Using nuclear weapons first against Russia and China would endanger our and our allies’ very survival by encouraging full-scale retaliation. Any first use against lesser threats, such as countries or terrorist groups with chemical and biological weapons, would be gratuitous; there are alternative means of countering those threats. Such use against North Korea would be likely to result in the blanketing of Japan and possibly South Korea with deadly radioactive fallout.

But beyond reducing those dangers, ruling out first use would also bring myriad benefits. To start, it would reduce the risk of a first strike against us during global crises. Leaders of other countries would be calmed by the knowledge that the United States viewed its own weapons as deterrents to nuclear warfare, not as tools of aggression.

The policy would also reduce costs by gutting the rationale for retaining the large arsenal of land-based strategic missiles in silos across the Midwest and the tactical nuclear weapons deployed in Europe. Those missiles are mainly for first-use; they are a risky option for second-use because they are highly vulnerable to enemy attack. Eliminating these weapons entirely would be the best option.

Phasing out land-based missiles and shifting to a reliance o­n submarines and bombers would save about $100 billion over the next three decades. The elimination of smaller, tactical nuclear weapons would save billions more. President Obama could begin the phaseout of land-based missiles before he left office by instructing the Department of Defense to remove 550 weapons from the operationally deployed category and transfer them to long-term storage, thereby reducing the operationally deployed inventory to about 1,000 strategic warheads. These missiles are surplus weapons no longer needed for deterrence.

A no-first-use policy would also reduce the risks of accidental or unauthorized use of nuclear weapons. By scrapping the vulnerable land-based missile force, any need for launching o­n warning disappears. Strategic bombers can be sent aloft o­n warning of an apparent incoming attack, which may or may not be a false alarm, and stay up until the situation clarifies. Strategic submarines are extremely survivable and exert no pressure o­n decision-makers to fire them quickly. They can patrol for months waiting for instructions. Both bombers and submarines are also less vulnerable to cyberwarfare than the strategic missiles o­n land.

Finally, no-first-use would help ensure that democratically elected officials maintained control over nuclear weapons. Savings from reducing the nuclear force could be invested in fortifying command centers and communications networks, which would better protect the president and ensure the continuity of government during a crisis. This would not o­nly fortify deterrence but also reduce the current possibility of a president’s losing control over nuclear operations at an early stage of conflict.

Beyond those benefits, we believe a no-first-use policy could catalyze multilateral negotiations to reduce nuclear arms, discourage nonnuclear states from developing them and reinforce the Nuclear Nonproliferation Treaty.

Although a no-first-use policy would limit the president’s discretion by imposing procedural and physical constraints o­n his or her ability to initiate the use of nuclear weapons, we believe such checks o­n the commander in chief would serve the national interest.

President Obama has an opportunity to further delegitimize nuclear weapons by adopting no-first-use as a core principle of United States security policy o­n the grounds that first-use is unnecessary and a threat to national survival and humanity itself. We could still maintain a robust nuclear umbrella to protect ourselves and our allies.

China and India adopted this policy long ago, and the American people overwhelmingly support it, according to a recent survey. In that poll, two-thirds say the United States should use nuclear weapons o­nly in response to a nuclear attack or not at all, while just 18 percent think that first-use may be justified sometimes.

President Obama would be wise to follow China’s example. As commander in chief, he can adopt no-first-use overnight and lead the way in establishing it as a global norm among all of the nine countries with nuclear weapons. The next president ought to stay that course. Our nation, our allies and indeed the world will be better and safer for it.

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James E. Cartwright, the chairman of the Global Zero Commission o­n Nuclear Risk Reduction, is a former vice chairman of the Joint Chiefs of Staff and former commander of the United States Strategic Command.

Bruce G. Blair is a research scholar at Princeton, a founder of Global Zero and a former Minuteman launch officer.

A version of this op-ed appears in print o­n August 15, 2016, o­n page A19 of the New York edition with the headline: End the First-Use Policy for Nuclear Weapons.